JPH02217287A - Optical recording medium - Google Patents

Abstract

PURPOSE:To improve image density and background color and to sufficiently read directly with the naked eye of a human being by providing an optical absorber dispersed or dissolved in solvent soluble or thermally fusible substance, and substance for coloring solely with heat or in reaction with other substance on a base material. CONSTITUTION:An optical absorber for absorbing a recording light to be thermally converted and discharged, dispersed or dissolved in solvent soluble or thermally fusible substance, and a substance for coloring with heat or in reaction with other substance are provided on a base material. Here, the absorber desirably includes, for example, near infrared light absorber, and the substance for coloring with the heat or in reaction with other substance desirably includes, for example, electron donative achromatic dye and/or electron acceptive acid substance. The acid substance desirably includes, for example, electron acceptive organic acid substance. The used fusible substance desirably includes, for example, a lower melting point than that of the substance for coloring in reaction with other substance. With this configuration a heat sensitive recording sheet manufacturing system can be easily employed, and even if the amount of the used absorber is small, sufficient image density and background color can be improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a recording method using light as a recording source, which records data readable to the naked eye by using a substance that converts absorbed light into heat and emits it. It's about the body.

(Prior technology) Among the face-to-face recording methods that do not require development or fixing, thermal recording paper that uses basic dyes and organic color developers as coloring agents is easy to operate and maintain, making it suitable for facsimiles and printers. Widely used.

However, this method cannot be used with thermal heads or heat-generating ICs.
Because the pen is brought into direct contact with thermal recording paper to heat and record, colored molten matter adheres to the thermal head and heat-generating IC pen, causing problems such as adhesion of residue and sticking.
There were problems with recording failures and recording quality.

Particularly in the case of continuous line drawing in the recording flow direction, such as with a plotter printer, it has been impossible to perform continuous printing without causing problems such as adhesion of residue.

Furthermore, in the recording method using a thermal head, it is said to be difficult to increase the image resolution to 8 lines/square or more.

Therefore, a non-contact recording method using light has been proposed as a method of eliminating problems such as adhesion of residue and sticking and further improving resolution.

JP-A No. 54-4142 discloses that in a heat-sensitive recording material in which a heat-sensitive recording layer containing leuco dye as a main component is coated on a support, a metal compound having lattice defects is used. It is disclosed that thermal recording is possible by absorbing light in the visible and infrared regions and converting it into heat.

JP-A-58-209594 discloses an optical recording medium in which at least one set of a near-infrared absorber and a heat-sensitive coloring material having an absorption wavelength in the near-infrared region of 0.8 to 2 μm are laminated on a substrate. JP-A-58-94494 discloses that one or more heat-sensitive coloring materials and one or more near-infrared compounds consisting of a compound having a maximum absorption wavelength in near-infrared light of 0.7 to 3 μm. The present invention discloses a recording medium formed by coating a base material with an external absorbent, and discloses that recording on these recording media can be performed using a hot plate and a laser beam having a wavelength around near infrared. ing.

JP-A-58-94494 and JP-A-58-209
No. 594 discloses a method in which a near-infrared absorber is directly added to a material for a thermosensitive coloring layer to form a coating material, and the coating is dried to obtain a light-absorbing thermosensitive coloring layer. However, this method has a desensitizing effect and a coloring effect on the heat-sensitive color-forming material, and most of them impair the color-forming property and background color, so it is difficult to select a usable near-infrared absorbing material and is not practical. As a countermeasure to this problem, it has been proposed to include a near-infrared absorbing layer in a layer separate from the heat-sensitive coloring layer and to use the layer in a laminated manner, but the more multi-layered the structure, the more disadvantageous it becomes in terms of manufacturing.

The near-infrared absorbers disclosed in these publications are cyanine dyes, thiol nickel complexes, and squarylium dyes. In addition to this, near-infrared absorbers include nitroso compounds and their metal complexes, polymethine dyes (cyanine dyes), thiols and cobalts, which are listed in "Near Infrared Absorbing Pigments J (Kagaku Kogyo 43, May 1986 issue)." Or a complex with palladium.

Phthalocyanine dyes, triallylmethane dyes.

Immonium or diimmonium dyes and naphthoquinone dyes are known.

(Problems to be Solved by the Invention) All of the above-mentioned known near-infrared absorbers are quite strongly colored, so optical recording materials using them as they are have poor background color, and these near-infrared absorbers When the agent is directly incorporated into the heat-sensitive coloring material, both have a desensitizing effect and the coloring density is not sufficient.

If the optical recording medium is an optical disc, since optical discs are mechanically readable, it is sufficient to obtain optical contrast at the reading wavelength, but in order for humans to directly read the recorded information with the naked eye, image density and Contrast that can be read from the ground color is required, but the above-mentioned method of using the known near-infrared absorber has insufficient contrast.

In view of this situation, we are using light absorbers that absorb light other than visible light, especially low-power laser light with a dominant wavelength around near infrared, and emit it as heat, and substances that develop color due to heat. The object of the present invention is to obtain an optical recording medium which has a high image density (good background color) and a sufficient contrast to be directly readable by humans with the naked eye.

(Means for Solving the Problem) The above problem is achieved by reacting an optical recording medium with a light absorbing agent dispersed or dissolved in a solvent-soluble or thermofusible substance alone or with another substance to generate color. This problem was solved by providing a substance on the base material. Moreover, this problem is solved by adding an electron-donating colorless dye and an electron-accepting acidic substance to a heat-sensitive coloring layer containing an electron-donating colorless dye and an electron-accepting acidic substance, which react with heat to form a color. By making an optical recording medium containing a near-infrared light absorber in a thermofusible substance that can be dissolved and has a lower melting point than the electron-donating colorless dye and/or the electron-accepting acidic substance. well resolved.

The light absorbent of the present invention is a substance that absorbs light from a recording source, converts the absorbed light into heat, and releases the heat to the outside. The light absorber absorbs the light from the recording source as widely as possible and converts it into heat. The heat conversion efficiency and the amount of heat generated are determined by the fact that the maximum absorption wavelength of the light absorber and the dominant wavelength of the recording light match or are close to each other. It is preferable in this respect. In order to obtain a record suitable for reading with the naked eye, it is preferable that the maximum absorption wavelength of the light absorbent and the main wavelength of the recording light source are outside the visible region, and the light absorber has a maximum absorption wavelength in the visible region. The agent has a specific hue and is strongly colored, making it suitable only for specific uses.

The light that is the recording source is not particularly limited, but it is possible to obtain light intensity with a small and simple device that allows the light absorber to generate enough heat to sufficiently color a substance that develops color due to heat. It is preferable that the light is easy to collect and the light is safe. From this point of view, laser light having a main wavelength in the near-infrared region is currently the most preferred.

Most near-infrared absorbers are substances that absorb light having a dominant wavelength in the near-infrared region and convert it into heat. This near-infrared absorber may be one that has absorption in the near-infrared region of 0.7 to 3 mμ, and is known from Japanese Patent Application Laid-Open No. 54-41
No. 42, JP-A-58-209594, JP-A-58-9
In addition to cyanine dyes, thiol nickel complexes, and squarylium dyes disclosed in Publication No. 4494, nitroso compounds and their metal complexes in "Near Infrared Absorbing Dyes" (Kagaku Kogyo 43, May 1986 issue), polymethine-based Pigments (cyanine dyes), complexes of thiol and cobalt or palladium, phthalocyanine dyes, triallylmethane dyes, immonium or diimmonium dyes, naphthoquinone dyes, or discovered by the present inventors in February 1999. 1, 3-diphenylthiourea and 1 described in the specification filed with the Japan Patent Office on the 6th.
, 3-Dibenzylthiourea and other thiourea derivatives and organic acid salts, alcoholades, or hydroxides of metals with an atomic weight of 40 or more excluding those in Groups IA and IIA of the periodic table are mixed and heat-treated. Or, with a dispersible near-infrared absorber such as copper sulfide or graphite, which is described in Japanese Patent Application No. 63-272702 filed by the present inventors regarding an optical recording medium using a dispersible near-infrared absorber. be.

Examples of the substance of the present invention that develops color by heat alone or by reacting with other substances include the following substances.

Typically, substances that develop color by reacting with other substances include:
There are known components of thermosensitive recording paper consisting of an electron-donating colorless dye and an electron-accepting organic color developer.

Examples of electron-donating colorless dyes include triphenylmethane-based dyes such as crystal violet lactone, fluoran-based dyes such as 3-diethylamino-6-methyl-7-anilinofluorane, and 3-(4-diethylamine-2-ethoxyphenyl)- 3-(1-ethyl-2-methylindole-3-
Typical examples include leuco dyes such as azaphthalide dyes such as yl)-4-azaphthalide, or fluorein dyes such as 3゜6,6-)lis(dimethylamino)spiro[fluorein-9,3-phthalide]. be able to.

Examples of electron-accepting organic color developers include bisphenol A,
4-hydroxybenzoic acid ester, 4-hydroxyphthalic acid diester, phthalic acid monoester, bis-(
Hydroxyphenyl) phenyl sulfides, 4-hydroxyphenylaryl sulfones, 4-hydroxyphenylaryl sulfonates, l,3-di[2-(hydroxyphenyl)-2-propyltobenzenes, 4
-Hydroxybenzoyloxybenzoic acid esters, bisphenol sulfones, etc. Details of these materials are disclosed in, for example, Japanese Unexamined Patent Publication No. 187082/1982.

In addition, when providing a heat-sensitive coloring layer using a substance that develops color by itself or by reacting with other substances,
As with conventional thermal recording paper, these substances that develop color by heating alone or by reacting with other substances are usually used as binders, white pigments, sensitizers, stabilizers for colored images, or to improve the slipperiness of the recording layer. It can be obtained by adding a quality adjusting agent to suitably adjust other qualities to form a paint and applying it onto a base material. Specific examples of the binder, the white pigment, the sensitizer, the color image stabilizer, or the quality control agent include those described in many known documents related to heat-sensitive recording, including JP-A-62-187082.

The feature of the present invention is that, as described in JP-A-58-209594 or JP-A-58-94494, a light absorbing agent that absorbs recording light and converts it into heat is directly added to a thermosensitive coloring material. Rather than adding the light absorbent to the recording light and converting it into heat, the light absorber is first dispersed or dissolved in a solvent-soluble or heat-fusible substance, then finely pulverized, and then added to the heat-sensitive coloring material. There are characteristics in its use.

The thermofusible substance used in the present invention is not particularly limited as long as it has a melting point equivalent to or has a lower melting point than a substance that develops color when heated alone or by reacting with another substance, and is used in the field of thermal recording paper. Any of the dyes, color developers, sensitizers, image stabilizers, and other quality control agents that meet the above conditions may be used.

Among these, sensitizers are particularly suitable; among them, the compounds shown below are neutral, have few functional groups, and have lower melting points than substances that, when melted, develop color when heated alone or by reacting with other substances. It is particularly preferable because it can dissolve both of them.

Thermofusible substances other than the above include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montan wax, polyethylene wax, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p- Tricarbonate, p-benzylbiphenyl, phenyl-α-naphthyl carbonate, 1.
Examples include 4-jethoxynaphthalene, 1-hydroboxy-2-naphthoic acid phenyl ester, and 1,2-di(3-methylphenoxy)ethylene.

These thermofusible substances may be used alone or in combination of two or more.

In order to incorporate light absorbers into these thermofusible materials,
The light absorbing agent may be mixed into the heat-fusible substance and melted and dissolved or dispersed, or the heat-fusible substance and the light absorbent may be mixed in advance and heated and melted.O Solvent in the present invention The soluble substance refers to a solvent-soluble one among the thermofusible substances mentioned above, or a substance that develops color alone or by reacting with another substance, and the above-mentioned thermosensitive coloring material, that is, a thermochromic material that develops color when heated alone, or It is an electron-donating colorless dye or an electron-accepting color developer. Optionally, it may also be an image stabilizer or other quality control agent.

As an image stabilizer, phthalic acid monoester metal salt, p
-tertiary-butylbenzoic acid metal salts, nitrobenzoic acid metal salts, and the like.

Other quality control agents include anti-sticking agents such as fatty acid metal salts, pressure coloring inhibitors such as fatty acid amides, ethylene bisamide, montan wax, and polyethylene wax, sodium dioctyl sulfosuccinate,
Dispersants such as sodium dodecylbenzenesulfonate, sodium laurate, sodium lauryl alcohol sulfate, alginic acid, benzophenone-based and triazole-based ultraviolet absorbers, and other known antifoaming agents that can be used in dye-based thermal recording paper. , optical brighteners, water-resistant agents, etc.

The light-absorbing material can be added to a solution of these solvent-soluble substances, or added to the solvent together with these solvent-soluble substances, mixed uniformly to dissolve or disperse it, and then remove the solvent. Created by If the light-absorbing material does not dissolve or is difficult to dissolve in a solvent, it may be used as is or after being pulverized into fine particles using a grinder such as a sand grinder or a dispersion machine together with a suitable dispersant. The finer the degree of atomization, the better, but at least 3μ or less,
More preferably, it is finely pulverized to 1 μm or less.

The light absorbent dispersed or dissolved in a solvent-soluble or thermofusible material obtained as described above can be processed using an attritor sand grinder in the same way as ordinary heat-sensitive materials.
Usually o, i with a grinder or dispersion machine such as a ball mill.
It is wet-milled to about 3 μm and mixed uniformly with other necessary materials to form a coating solution.

For example, if the solvent-soluble or thermofusible substance is a dye that develops color when heated alone, a light absorber is dissolved together with the dye in a solvent, the mixture is dried to remove the solvent, and the mixture is pulverized to form a white binder. It is mixed with pigments, sensitizers, quality control agents, etc. to make a coating liquid.

If the solvent-soluble or thermofusible substance is a so-called sensitizer with a lower melting point than at least one of the thermosensitive coloring materials,
A light absorber is uniformly mixed into the heat-molten thermofusible substance, cooled and finely pulverized, and the sensitizer containing the light absorber is mixed alone or by reacting with other substances. It is mixed with color-forming heat-sensitive material, binder, white pigment, quality control agent, etc. to form a coating liquid. In this case, a sensitizer that is the same as or different from the sensitizer containing the light absorber may be further added.

When the sensitizer containing a light absorber does not sufficiently dissolve the heat-sensitive color former when melted, it is preferable to use another light absorber that dissolves the heat-sensitive color former when melted.

A solvent-soluble or thermofusible substance is one of the substances that develops color by reacting with another substance due to heat, for example, in the case of an electron-accepting organic developer, the electron-accepting organic developer and the light-absorbing agent are combined in a solvent. The electron-accepting organic color developer containing the light absorbing agent is mixed with an electron-donating colorless dye and a white binder. Mix uniformly with pigments, sensitizers, quality control agents, etc. to make a coating solution.

The binder used in this coating solution has a polymerization degree of 2.
Completely saponified polyvinyl alcohol of 00 to 1900, modified polyvinyl alcohol such as amide-modified polyvinyl alcohol, hydroxyethyl cellulose, styrene-butadiene copolymer, and the like.

As the white pigment, organic and inorganic fillers commonly used in the paper processing field, such as clay calcium carbonate or plastic pigments, can be added. especially,
Hollow plastic pigments are preferred because they reflect light well and have good heat retention properties. The various materials used in these heat-sensitive coloring layers include basic colorless dyes, organic color developers, binders, sensitizers, fillers, and qualities described in Japanese Patent Application No. 1983-272702 filed by the inventors of the present application. Modifiers can equally be used in the present invention.

The types and amounts of the electron-donating colorless dye, electron-accepting acidic substance, binder, sensitizer, filler, and other various components in the coloring layer used in the present invention are determined according to the required performance and recording suitability. Although not particularly limited, usually 3 to 12 parts of an electron-accepting acidic substance and 3 to 1 part of a sensitizer to 1 part of an electron-donating colorless dye and an electron-accepting acidic substance.
2 parts, 1 to 20 parts of filler, and 10 to 25 parts of binder based on the total solid content of the coloring layer.

The coating liquid thus obtained is coated onto a substrate using a general paper coating machine such as a bar coater, air knife coater, or blade coater to obtain an optical recording medium. The base material is not particularly limited, but from the viewpoint of ease of coating with a water-based paint, base paper mixed with fibers or the like as necessary for the valve is most commonly used.

It is a preferable method to provide a protective layer on the surface of the thermosensitive coloring layer to reduce or prevent contamination from the external environment such as moisture, gas, water, solvent, oil, etc.

The protective layer is preferably one that is transparent to visible light and recording light and does not have an adverse effect on the thermosensitive coloring layer, and one or more binders are selected from among the binders normally used for the thermosensitive coloring layer.

Alternatively, a light absorbing layer may be provided in which the protective layer contains a small amount of a light absorbing agent that is dissolved in water or a solvent and absorbs as little visible light as possible, and is dissolved or dispersed in a binder.

(Function) As described above, by using a light absorbing agent dispersed or dissolved in a solvent-soluble or thermofusible substance together with a heat-sensitive coloring material, it is possible to achieve high image density, good ground color, and direct human contact. The reason why an optical recording medium with sufficient contrast to be read with the naked eye is obtained is not clear, but it is thought to be related to the following.

(1) If the light absorber is contained in a thermofusible substance (sensitizer) with a lower melting point than the heat-sensitive coloring agent, the heat generated when the light absorber absorbs the recording light is immediately absorbed. The sensitizer around the light-absorbing side is melted, and the melted sensitizer melts and mixes the heat-sensitive color-forming component in the immediate vicinity, thereby producing a coloring phenomenon. That is, by using a sensitizer with a light absorption function, the melting of the sensitizer, which is rate-limiting, is accelerated, resulting in better color development.

(2) Since the light absorber exists in close proximity to the heat-sensitive coloring component, the energy converted from light to heat is transmitted quickly and effectively, and is limited to the area where the light is absorbed, resulting in color development. In addition to being faster, image density and resolution are also improved.

(3) The light absorber does not come into direct contact with the heat-sensitive coloring component, and
Because it is contained in other colorless substances, the coloring peculiar to the light-absorbing side is hidden, and when mixed with other heat-sensitive coloring ingredients, there is little coloration in the coating liquid, and even after it is applied, it reacts with each other. Since adverse effects such as coloring and desensitization are less likely to occur, the background color of the optical recording medium is improved and the contrast of the image to the naked eye is improved.

(Example) Next, an example of the present invention will be described. Parts and percentages in the examples are by weight.

Further, the optical recording media obtained in the following Examples and Comparative Examples were evaluated in terms of the color density of the recording spot and the background color using the following methods, and the results are shown in Table 1.

Density of recorded image (colored spot): Measured using a microdensitometer (PDM-5 manufactured by Konishiroku Photo Industry Co., Ltd.), and the measured value was converted to Macbeth density.

Background color of optical recording paper: Measured with a Macbeth densitometer.

Actual tl Electron-donating colorless dye dispersion (liquid A), electron-accepting acidic substance dispersion (liquid B), and light-absorbing sensitizer dispersion (liquid C) having the following compositions were each mixed separately in a sand grinder. After time-source grinding, 7.3 parts of liquid A, 30 parts of liquid B, and 20 parts of liquid C were added with silica (Mizukasil P-52
7. 25 parts of a 25% aqueous dispersion (manufactured by Mizusawa Chemical Co., Ltd.) and 1
10 parts of a 0% PVA aqueous solution is mixed to make a heat-sensitive coloring coating liquid containing a light absorption side, and this coating liquid has a basis weight of 60 g/n? 5 g/n? The coating was applied and dried to obtain optical recording paper.

(A) Liquid: Electron-donating colorless dye dispersion Black coloring dye: OD8 2.0 parts 10% PVA aqueous solution 3.4 parts Water 1.9 parts OD
B: 3-diethylamino-6-methyl=7-anirite fluorane (B) Solution: Electron-accepting acidic substance dispersion Color developer: BPA 6.0 parts 10% PVA aqueous solution 15.0 parts Water 9. 0 parts BPA: Bisphenol A (C) Liquid: Light absorption side content dispersion 49 parts of parabenzyl biphenyl (PBB), a sensitizer for heat-sensitive color recording paper, as a heat-fusible substance, and near-infrared light as a light absorber. Absorbent NK-125 (Japan Photosensitive Color Research Institute Co., Ltd.)
and 1 part of the maximum absorption wavelength 741 mμ),
The mixture was heated to 50° C. to melt and mix. After cooling, use a sand grinder to reduce the average particle size to 1. It was pulverized to 5 μm to obtain a light absorbent-containing material.

4.0 parts of the above light-absorbing agent-containing 10% PVA aqueous solution 10.0 parts of water
6.0 parts A semiconductor laser head (laser diode collimator head LDC-8330-CINC; manufactured by Abride Optec, center wavelength 830 nm, output 30 mW) was attached to the optical recording paper thus prepared, and a light condenser was attached to the optical recording paper thus prepared. Laser light was irradiated to perform optical printing using the apparatus shown in FIG. 1, which was combined with a lens (manufactured by Olympus Optical Co., Ltd., MD PLAN 5.0.1). The irradiation time was 11,500 seconds.

The sensitizer containing the light absorption side of Example 1 was replaced with the near-infrared absorber NK-
125 is equivalent to half of Example 1, 0°5 g (!:
An optical recording paper was obtained in exactly the same manner as in Example 1, except that 49.5 parts of L and parabenzyl biphenyl were used.

In Example 1 of "Big I Week", near-infrared absorber NK-1 to be melt-mixed
0.25 instead of 1 part. 5 parts, and the sensitizer MPE49 with the following structure was used instead of parabenzyl biphenyl.
．． An optical recording paper was obtained in exactly the same manner as in Example 1 except that the mixture was melted and mixed into 5 parts.

The light absorber-containing material of Example 1 of Shinkangoko was replaced with near-infrared absorber NK-12.
5 and 49 parts of parabenzyl biphenyl were added to 300 parts of acetone, stirred to form a homogeneous mixture, then distilled under reduced pressure to remove acetone, and milled with a ball mill to about 1 μm.
It was obtained by finely pulverizing it.

Using 4 parts of this light-absorbing agent-containing material, a light-absorbing material-containing dispersion liquid was prepared in the same manner as Example 1 (7) Liquid C, and an optical recording pair was obtained in the same manner as in Example 1.

In Example 1, the electron-donating colorless dye, electron-accepting acidic substance, thermofusible substance, light-absorbing agent, and the addition ratio of the light-absorbing agent to the thermofusible substance were An optical recording medium was obtained in the same manner as in Example 1, except for the changes shown in Table 1.

In Table 1, the abbreviations and abbreviations of materials other than those described in Example 1 described in each column and in each column are as follows.

Dye: Abbreviation for electron-donating colorless dye; Developer: Abbreviation for electron-accepting acidic substance; Sensitizer: Abbreviation for thermofusible substance; 0DB-2 in the dye column: dibutylamide/-6-methyl-7- Anilitufluorane S-205: 3- (N-ethyl-N-isoamyl)
POB in the column for -6-methyl-7-anirithufluoran color developer: Also in the column for p-hydroxybenzoic acid benzyl ester sensitizer, to the right of the abbreviations for the types of color developer, sensitizer, and light-absorbing material. A shoulder dash (') indicates that these were used in a form containing a light absorber.

NK-123 in the light absorber column: A near-infrared absorber with a maximum absorption wavelength of 817 mμ, manufactured by Nippon Kanko Shiki Kenkyusho Co., Ltd.

NK-2268: Manufactured by Nippon Kanko Shiki Kenkyusho Co., Ltd., a near-infrared absorber with a maximum absorption wavelength of 831 mμ.

NK-2014: Manufactured by Nippon Kanko Shiki Kenkyusho Co., Ltd., near-infrared absorber with a maximum absorption wavelength of 778 mμ.

ICl511651G/2: Manufactured by ICl, a near-infrared absorber with a maximum absorption wavelength of 770 mμ.

According to Table 1, an optical recording medium containing a light absorber in a thermofusible substance (sensitizer) has a sufficient amount of light absorber, even though the amount of light absorber used is extremely small. It is clear that a recording density can be obtained.

In liquid C of Example 1, the thermofusible substance used in Examples 1 and 3 was used as a sensitizer instead of the light-absorbing substance. Optical recording paper was prepared in the same manner as in Example 1, except that the same amount was used, and the recording was evaluated. The results are shown in Table 1.

In this comparative example, conventional thermal recording paper was used as an optical recording medium, and as is clear from Table 1 showing the evaluation, thermal recording paper that does not contain a light absorber does not develop any color when exposed to light.

Salt Mosquito 51 This comparative example does not contain a light absorbent in the thermofusible material,
This is an example in which a light absorber and a sensitizer, which is a heat-fusible substance, are simply mixed into a heat-sensitive color former dispersion liquid separately.

In the C liquid of Example 1, the near-infrared absorber ICl51165 manufactured by ICI used in Examples 5 and 7 was used as a light absorber.
10/2 and PBB used in Example 1 as a sensitizer,
The dispersion liquids (C1) and (C2) were prepared in the same manner as in Example 1 except that 0.8 parts of C1 liquid and 20 parts of C2 liquid were added in place of C liquid in Example 1. A record was created and evaluated.

The results are shown in Table 1. Note that the amount of the light absorber used was 1% of the sensitizer PBB.

(CI) Liquid: Light absorption side dispersion 1 part light absorber 19 parts water The mixture was vigorously stirred with a stirrer to prepare a dispersion.

(C2) Solution: Sensitizer dispersion Sensitizer 4 parts 10% PVA aqueous solution 10 parts Water 6 parts These were vigorously stirred with a stirrer to form a dispersion.

As is clear from Table 1, although the amounts of light absorber and sensitizer used in this comparative example are almost the same as in the examples, the ground color and color density are insufficient compared to the examples. .

This comparative example is an example in which a light absorber is placed below the heat-sensitive coloring layer.

Near-infrared absorber NK used in Example 1 as a light absorber
A dispersion of -125 having the following formulation was prepared and applied to the high-quality paper used in Example 1 at 0.1 g/rrr (solid content) to form a light absorption layer. On this light absorption layer, exactly the same as in Comparative Example 1,
An optical recording medium of Comparative Example 4 was prepared by applying a heat-sensitive coloring layer containing a sensitizer at a rate of 5 g/rd, and the recording was evaluated in the same manner as in Example 1. The amount of light absorbent used in this comparative example was 0.05 g/r.
rr, and Example 1 corresponds to 0.02 g/rd, so even though this comparative example uses 2.5 times more light absorbent than Example 1, from Table 1, As is clear,
The background color and color density of this comparative example are significantly inferior to those of Example 1.

This comparative example is an example in which a light absorber is placed below the heat-sensitive coloring layer.

The optical recording paper of Comparative Example 5 was prepared by applying 0.1 g/rd of the light-absorbing dispersion of Comparative Example 4 onto the optical recording paper prepared in Comparative Example 1 to provide a light-absorbing layer on the heat-sensitive recording layer. It was prepared and recorded and evaluated in the same manner as in Example 1. As is clear from Table 1, although this comparative example also used a larger amount of light absorbent than Example 1, the color density was significantly inferior to that of Example 1.

The color developer POA (p-hydroxybenzoic acid benzyl ester) used in Example 7 is a heat-melting substance, and this POB
In 49.75 parts, the near-infrared absorber N used in Example 1 was added.
0.25 parts of K-125 was added and melted at about 120°C to form a homogeneous mixture, which was then cooled and atomized to an average particle size of 0.9μ using an attritor. 10 parts of a 10% PVA aqueous solution and 6 parts of water were added to 4 parts of the light-absorbing agent-containing material thus obtained, and the mixture was wet-milled for 1 hour using a sand grinder to obtain a light-absorbing side-containing color developer dispersion. .

To 20 parts of the light-absorbing color developer dispersion thus obtained, 7.3 parts of solution A of Example 1, 25 parts of the 25% silicate dispersion, and 10 parts of the 10% PVA aqueous solution were mixed, and then the light A heat-sensitive coloring coating liquid containing absorption side is used, and this coating liquid has a basis weight of 60 g/n? An optical recording paper was obtained by applying 5 g/d on a high-quality paper using a Meyer bar and drying. For this optical recording paper, a semiconductor laser head (laser diode collimator head LDC-8330-CINC;
(manufactured by Abride Optec) with a numerical aperture of 0.
A circular black recording line was obtained by recording at a moving speed of 1.5 mm per second using a rotating stage using an apparatus combined with 28 condensing lenses. As shown in Table 1, this optical recording paper had good ground color, good image density, and good foundation last.

IC1116510 (I C
Manufactured by one company, maximum absorption wavelength 765 mμ) 10% pvA
It was dissolved in 19 parts of an aqueous solution to obtain a near-infrared absorber solution with a concentration of 5%. On the optical recording paper obtained in Example 1, 1 g/rd of this 5% concentration near-infrared absorber solution was applied using a Mayer bar to provide a light-absorbing layer and a protective layer, and the light-absorbing agent was added to the thermosensitive coloring layer. N.K.
-125 and a light absorber IC1116510 in the protective layer.

When this recording paper was recorded with the apparatus of Example 1O, Table 1
As shown in Figure 2, an image with extremely high optical density was obtained. Also,
This optical recording paper had a faster color development start-up with respect to the recording light than the optical recording paper of Example 1.

(Effect of the invention) As explained above, by dispersing or dissolving the light absorbing agent in a solvent-soluble or thermofusible substance, the light-absorbing material is used as a light-absorbing layer without being separated from the coloring layer. Since it can be incorporated into the color forming layer, it can be easily incorporated into a thermal recording paper manufacturing system, and it is advantageous in terms of manufacturing since it does not require a multilayer structure. or,
Compared to the case where a multilayer structure is used as a light absorbing layer, an optical recording medium with sufficient image density and good background color can be obtained by using a small amount of light absorbent.

By discovering a method with these advantages, we have made it possible to use a compact semiconductor laser with a stable output to perform heat mode recording with a lump last that can be discerned with the naked eye, and to put optical recording media into practical use. This has brought good results in promoting the development of

[Brief explanation of the drawing]

Figure 1 is a block diagram of a laser beam recording device. 1... Laser diode collimator head, 2... Shutter 3... Condensing lens group, 4... Optical recording paper,
5...Power supply Figure 1 - Diode collimator head group

Claims (6)

[Claims] (1) A base material consisting of a light-absorbing agent that absorbs recording light, converts it into heat, and releases it, which is dispersed or dissolved in a solvent-soluble or thermofusible substance, and a substance that develops color by reacting with other substances when heated. An optical recording medium characterized by being provided on the top. (2) The optical recording medium according to claim 1, wherein the light absorbent is a near-infrared light absorbent. (3) Substances that react with other substances and develop color due to heat,
The optical recording material according to claim 1 or 2, which is an electron-donating colorless dye and/or an electron-accepting acidic substance. (4) The optical recording medium according to claim 3, wherein the electron-accepting acidic substance is an electron-accepting organic acidic substance. (5) Claims 1, 2, and 3, wherein the thermofusible substance has a lower melting point than a substance that develops color by reacting with another substance.
and 4. The optical recording medium according to 4. (6) Dissolving the electron-donating colorless dye and the electron-accepting acidic substance during thermal melting into a heat-sensitive coloring layer containing the electron-donating colorless dye and the electron-accepting acidic substance, which develops color by reacting with heat. An optical recording medium characterized in that a near-infrared absorber is contained in a thermofusible substance having a lower melting point than the electron-donating colorless dye and/or the electron-accepting acidic substance.